KYB KG5551 Shock Absorber - Rear

KYB Gas-a-just Rear Shock for Classic Ford

The KYB Gas-a-just KG5551 is a monotube suspension shock absorber built for classic Ford and Mercury rear applications that need firmer control and consistent response. It is engineered for vehicles that work harder than stock, including Mustang and Capri setups with performance-oriented suspension tuning.

Gas-a-just Product Line

KYB Gas-a-just shocks use a high-pressure monotube design with separate gas and oil chambers for quick response and fade-resistant operation. The KG5551 is part of KYB’s Gas-a-just line, which is aimed at rear suspension upgrades where added damping, steering response, and control are important.

Key Features

• Part number KG5551
• Monotube shock absorber design for consistent damping
• Up to 25% more damping performance than original equipment shocks
• High-pressure nitrogen gas and hydraulic separation for fade-free operation
• Triple chrome plated piston rod helps reduce seal wear and fluid leakage
• Additional damping for vehicles with heavier tires, wheels, or towing demands
• Designed specifically for classic Ford car applications
• Dust cover included

Detailed Description

The KYB Gas-a-just KG5551 is built to improve rear suspension control on 1978-1993 Ford Mustang, 1983-1986 Ford Mustang, 1983-1986 Mercury Capri, 1978-1981 Ford Fairmont, 1979-1981 Mercury Capri, and 1978-1981 Mercury Zephyr rear applications listed below. Its monotube construction separates gas and oil to maintain stable damping under repeated use, while the higher gas pressure helps the shock react quickly to steering and body-motion changes. This part cross-references Monroe Shocks & Struts (e.g., 5845) for the same application.

What It Helps Address

• Excessive rear-end bounce after bumps
• Reduced control during spirited driving or load changes
• Shock fade from repeated suspension movement
• Loose rear suspension feel on classic Ford chassis
• Wear related to leaking or weakened shock absorbers

Installation Notes and Fitment

• Fits 1984-1993 Ford Mustang, rear
• Fits 1979-1982 Ford Mustang, rear
• Fits 1987-1989 Ford Mustang, rear; w/ Saleen Package
• Fits 1983-1986 Ford Mustang, rear; Special Handling
• Fits 1983-1986 Mercury Capri, rear; w/ Special Handling Package
• Fits 1978-1981 Ford Fairmont, rear; (Exc. TRX Suspension)
• Fits 1979-1981 Mercury Capri, rear
• Fits 1978-1981 Mercury Zephyr, rear; (Exc. TRX Suspension)

Verify compressed length 12.6, extended length 20.67, and stroke length 8.07 before installation. Lower mount type is E2(12.8X38) and upper mount type is S1. Dust cover is included; internal rebound spring, B-stop, and R-stop are not included.

Quality Assurance

KYB designs the Gas-a-just line for performance-focused damping control and consistent operation in demanding suspension conditions. The KG5551 uses a high-pressure monotube layout and a triple chrome plated piston rod to support long-term seal durability and stable rear shock performance.